not very similar with a human brain. the only thing I know about a rat's brain is that it disproved the belief that the number of circumvolutions is directly proportional to the intelligence of the animal. the rat has few circumvolutions, but is rather intelligent

"As a biologist, I firmly believe that when you're dead, you're dead. Except for what you live behind in history. That's the only afterlife" - J. Craig Venter